Drivetrain Builder
Servo motor sizing: configure motor, gear stages, and output.
Advanced
Output shown as RPM by default.
Advanced
Fill these to see deviation from your calculated output.
Results
Linear Output
Feed Constant
Target Comparison
Inertia Matching
Inertia ratio exceeds 10:1. Consider a higher gear ratio or a motor with more rotor inertia.
Stage Breakdown
| Stage | Ratio | Efficiency |
|---|
Questions
How do I size a servo motor?
Work from the load back to the motor: required output speed and torque, then pick a gear ratio that lands the reflected inertia between 1:1 and 10:1 relative to the motor's rotor inertia. The Drivetrain Calculator shows the inertia match live as you edit.
What is an acceptable inertia ratio?
Between 1:1 and 10:1 reflected-load-to-motor inertia is the standard servo tuning range. Above 10:1 the motor starts to lose bandwidth and settling time rises. MotionConvert warns above 10:1 for this reason.
How is output torque calculated?
Output torque equals motor torque multiplied by the total gear ratio and by each stage's efficiency. Each gear stage's efficiency defaults to 100% (no loss) if left blank.
What's the difference between rotation and linear output?
Rotation output reports RPM at the last stage. Linear output converts that RPM into m/s (or another linear-speed unit) using a roll circumference, a roll diameter, or a spindle lead, depending on which output mode you pick.
Can I stack multiple gear stages?
Yes. Anonymous and free users can stack up to two stages; Pro users up to ten; Expert users have no limit. Each stage takes a ratio, a pair of teeth or diameters, or a saved component.